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Multi-scale Investigation of the Effect of Stress History on the Mechanical and Deformation Characteristics of Marine Clay Using DEM Model
Yin Wang , Ziyi Pang, Yefeng Yang and Han Yang

Based on numerical simulations of triaxial tests, this paper investigates the effects of stress histories on the strength and deformation of marine clay from both macro and micro scales. By introducing the Elastic-Plastic Cemented contact model (EPC model) and a servo wall combination method, an extended DEM model is presented in our study. This novel method can effectively investigate the mechanical properties of marine clay. The validation and applicability of this simulation are achieved by comparing the numerical results and experimental data. The results indicate that the servo wall combination method effectively simulates the mechanical behavior and deformation characteristics of the soil in triaxial simulations. The EPC model accurately captures the stress-strain characteristics of soil stress history through plastic deformation. To investigate the influence of stress histories on the mechanical and deformation characteristics of soil, a consolidated drained triaxial DEM simulation of marine clay incorporating various over-consolidation ratios (OCRs) is conducted. It is observed that as the OCR increases, the soil sample experiences shear shrinkage, accompanied by a continuous increase in peak strength and a reduction in maximum volume shrinkage. Additionally, the porosity of the soil sample decreases while the coordination number of particles increases with an increase in OCR. Such macro and micro analyses demonstrate that increasing OCR enhances the total number of particle contacts and promotes the formation of more adhesion forces between particles. Consequently, the density and structural integrity of the soil are improved.

Keywords: Stress history, DEM simulation, Elastic-Plastic Cemented contact model, flexible film boundary, triaxial test, mechanical and deformation characteristics